The expert system computer program, version 2.0, is designed to assist and educate non-geophysicists in the use of geophysics at hazardous waste sites. A series of questions are asked about the site geology, contamination problem and cultural noise. Version 2.0 also contains a database of the physical and chemical properties of 94 substances selected from EPA's first priority list. The program considers the following geophysical methods: electromagnetic induction, d.c. resistivity, seismic, magnetic, ground penetrating radar, soil gas, gravity, and radiometric techniques. Based upon the answers given to the questions, the program provides a weighted recommendation of what types of geophysical methods will most likely be useful at the site to solve such problems as the location of the subsurface contamination and some hydrogeological characterization.